Device for cutting pipes

ABSTRACT

A pipe cutter for cutting pipes of plastic material. The pipe cutter has a clamp (2) for clamping the pipe and the clamp carries a saddle (9) which is rotatable about the clamp. A radially adjustable cutter (16) is mounted on the saddle (9) so that as the saddle (9) is rotated the pipe is cut. The cutter 16 is spring-loaded to accommodate for deflection of the pipe during cutting.

This invention relates to a device for cutting and/or shaping pipes andparticularly relates to the cutting of plastic pipes although theinvention is not necessarily limited thereto, and this invention hasparticular reference to the mounting of the cutters and the use ofcutters of particular type which will be later described herein.

BACKGROUND OF THE INVENTION

Pipes occur in very many sizes and larger sizes may be difficult to cutif an accurate end to the pipe is to be achieved.

Such cutting is usually done by a saw, either manually or mechanically,and difficulty occurs particularly where a pipe must be cut and perhapsthe end shaped on a site.

It is an object of the present invention to provide a pipe cutting andshaping tool which can be used on various pipe diameters and can be usedin the field in a simple and effective manner.

BRIEF DESCRIPTION OF THE INVENTION

The device according to this invention comprises a split yoke adapted tobe engaged on the pipe to be cut or shaped and locked thereto and on theyoke, a movable saddle which can move around on the yoke for the fullcircumference of the pipe and which carries a cutting tool and meanswhereby the saddle can be moved around on the yoke and includes meansfor adjusting the depth of cut and the position of cut.

The operation of the device is to clamp the yoke to the pipe adjacent towhere it is to be cut and to then engage the cutting tool and then movethe saddle around on the split yoke so that the cutting tool penetratesand channels the pipe, this action continuing with the cutting toolbeing fed in until the pipe has been cut and the cut portion severedfrom the main part of the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the pipe cutter,

FIG. 2 is a perspective view of the pipe cutter in the open position,

FIG. 3 is a further perspective view of the pipe cutter and

FIG. 4 is a view of the pipe cutter standing on its legs.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The pipe cutter 1 has a split yoke 2 formed in two parts hinged togetherby a hinge pin 3 and provided with a tensioning or locking lever 4 atthe other end to draw the ends together and to hold them when the yokeis tightened on to the pipe. The locking lever 4 is hinged to a springstrip 5 pivoted to one part, the lever 4 having a roller 6 to engage ina recess 7 in the other part. The split yoke 2 can have inserts whichcan be placed between the split yoke 2 and the pipe to allow differentsizes of the pipe to be cut by the one device, the inserts being eitherloose members fitted into position or members fitted to the split yokewhich can be displaced to make the yoke applicable when closed to pipesof different size, the inserts preferably being provided with means tolocate them correctly on the split yoke.

The yoke parts are so shaped that a runway 8 is formed which can beengaged by a saddle 9 to guide the saddle on the yoke 2, and the saddleitself is of circular form to fit into the split yoke and is split toextend fully around the split yoke. The saddle is either provided with ahandle 9' whereby it can be manually moved around on the yoke or it canbe driven by means of a motor or power applied from a drill or the like,and for this purpose the yoke can have a toothed section on it engagedby a pinion on the saddle whereby the saddle will be driven around theyoke.

Both the saddle 9 and the yoke 2 are centrally split to open out to beengageable on the pipe, the two parts of each being hinged together sothat when correctly positioned the two parts can open out together toencircle the pipe and then be closed together so that the saddle canrotate about the axis of the yoke. The yoke 2 has an internal groove orslot 8 which comprises the runway, and the saddle is generally U-shapedwith one leg 10 engaging in the slot 8, the other leg 11 extending overthe end face of the yoke 2 so that the saddle is carried in the shapedgroove or track 8 in the yoke to retain it in position on the yoke, thehinges of each being so arranged that the hinges operate about a commonaxis when the parts are correctly located, or as shown the saddle 9 canhave a chain line 12 between its two parts, the chain link being pivotedto each. Similarly the open ends are joined by a chain link 13, thislink being pivoted to one part, while the other has a recess 14 toengage the end of the link 13. Thus registration can readily be achievedby having a handle 15 on the yoke 2 which registers with the handle 9when the hinges are in registry.

The tool 16 is adjustably mounted on the saddle 9 and preferably is arotary cutting wheel, the tool being mounted in a tool support 17 whichis slidable radially in relation to the saddle and split yoke in asupport 18 on the saddle and preferably connected to a guide 19 and tothe handle 9' which extends outwardly through the support 18 and whichis provided with adjustment means for adjusting the cutting depth of thetool such as by having the handle rotational with threads 20 to moveinwards as the cut progresses but with the arrangement such that thetool remains correctly at its cutting angle.

The tool support 17 can be positioned so that the wheel 16 is at therequired extension from the saddle where it can operate on differentsized pipes, and the thread 20 holds the tool support 17 in any selectedposition by engaging a spring located latch 21 acting as a form ofratchet, so that rapid adjustment can be made by pushing on the handle9' while the fine adjustment of the cutting tool can be achieved byrotating the handle as the handle is pulled around to drive the saddlearound the yoke to channel the pipe. The spring loaded latch is releasedby pressing on the latch to allow rapid withdrawal of the tool.

The yoke is provided with the handle 15 which extends outwardly to allowthe operator to grasp the handle while manipulating the movable handle9', or alternatively the yoke could be fitted with two handles orsupport members or a single handle or support member with a ground plateso arranged that when a pipe is engaged in the split yoke, one end ofthe pipe can rest on the ground and the other will be elevated in thatthe split yoke will be elevated and supported from the ground by thefixed handle or similar assembly, this then allowing the moving handleto move the saddle around but keeping that handle clear of the ground.Alternatively, the handles can be replaced by other means and forinstance the handle which is used to move the saddle around on the yokecan be omitted and a power drive supplied for the saddle to move itaround on the yoke, or both a power drive and a handle can be provided,means being however necessary which will ensure that the tool is fedinto its work as it cuts the pipe. As staged earlier herein, the handlescan be used to index the position of the saddle relative to the yoke toalign the hinge of one with the hinge of the other to allow the yoke andsaddle to be opened out to be engaged on a pipe. Adjustment means can beprovided on the saddle to take up wear, such as adjusting screws orshims between the two edges as the halves close. Handle 15 is preferablyhollow, and can be unscrewed to expose a fixed rod or further handle 22,the handle 15 then being repositioned in a further socket 30 to form apair of legs as shown in FIG. 4.

The means for feeding the tool into the pipe as it is moved around thepipe to cut or shape it can be conveniently effected by a lead threadwhich moves the tool inwards having on it an indexing device such as amember having projecting fingers which engage pins on the yoke as thecarriage is moved around on the yoke, and by making the pins variable intheir position such as to give a greater or lesser space between themthe ratio of feed can be varied. As shown this feeding of the tool cantake place by manually rotating the handle 9' as desired.

The cutting tool can be replaced by a motorized cutter in the form of arouter having a shaped face which can first be caused to penetrate thepipe which is to be cut or shaped and can then be moved around to cutthe pipe by rotating the carriage on the yoke, this then allowing arequired shaping of the cut ends of the pipe to be achieved in a simplemanner by having a cutter of the required form.

As stated earlier the yoke can be provided with means whereby thediameter can be adjusted such as by having cam faces on the parts of theyoke operating in conjunction with movable inserts which allows themovable inserts to be engaged on the pipe to position the yoke at arequired distance from the pipe consistent with its diameter and thetool can then simply be fed into its initial cutting position by meansof any form of adjustment which may if required be independent of thefeed of the tool during its cutting operation, thus allowing the tool tobe prepositioned to suit a pipe of a particular diameter and to then befed by means of the indexing device or manually or by other means as thecarriage moves around on the yoke.

It will be realized that plastic pipes for which the device isparticularly suitable, but not limited thereto, are normally distortableand may not be perfectly round in cross-section but it will be realizedthat by having a yoke which is accurately shaped and which can be pulleddown firmly onto the pipe, that the yoke will serve as a means forholding the pipe accurately so that the cutter can operate in aneffective manner whether it to be a simple cutting tool or a shapingtool or a driven member such as a router.

A problem which occurs with cutters used in connection with this type ofapparatus is that the cutters tend to be heavily stressed because ofdistortion of material being cut and according to this invention,therefore, special forms of cutters are envisaged, or special mountingof such cutters occurs which will remove the problems resulting fromdistortion of the pipes as they are being cut even though they arefirmly held in a clamp adjacent to the area where the cutting is to takeplace.

To understand the problem it is necessary to appreciate that when acutter is forced into a pipe whether it be of a parting tool type or arotating type wheel cutter, the pipe is stressed inwards by the actionof the cutter and although the pipe is held in a clamp, some inwarddistortion of the pipe takes place with the result that after cutting,the pipe returns to its undistorted shape and the cutter therefore wouldtend to cut a slightly uneven end on such a pipe, which unevenness maybe barely noticeable but at the same time also because of this effectthere is a tendency to stress the cutter itself and in the case of awheel cutter to distort or break the cutter due to such stress.

The stress which occurs is largely a sideways stress on the cutter andit has been found that by allowing the cutter to move somewhat in alateral direction, that is in a direction parallel to the axis of thepipe being cut, the stress on the cutter is relieved and a better andmore accurate cut results.

The invention can be carried in to effect in various ways but accordingto one form, the circular cutter wheel 16 is mounted to rotate on ashaft 23 which is held during operation to be substantially parallel tothe axis of the pipe, which shaft 23 allows limited axial movement ofthe cutter 16 on the shaft but is spring-loaded by a spring 24 in such away that the cutter wheel 16 is urged against a stop to allow the cutterwheel 16 to move slightly on the shaft against this spring 24 toaccommodate itself correctly in a cut which is progressively being madeas the cutter is moved around the pipe to effect the cut.

The wheel cutter thus consists of a wheel mounted on a shaft with a stopto prevent the cutter moving towards the yoke but allowing it to moveoutwardly axially on the shaft against a loading which urges it toremain at the inward position.

The wheel cutter can be replaced by a parting tool type of cutter whichagain will be mounted so that it is urged into one cutting position butcan move outwards somewhat from this position against loading appliedagainst the cutter so that when a cut is being made, the cutter canfollow a groove which is formed by the cutter in its initial startingoperation and as the cutter is moved around the pipe during a cuttingaction the cutter can accommodate itself to the groove formed andcontinue to cut along the groove until that part of the pipe being cutoff from the main body of the pipe is severed.

Instead of using a single cutter it is possible to use a plurality ofcutters and, for instance, a cutter may be used which chamfers the pipebefore a wheel cutter is positioned to continue the cut, and in such anarrangement the cutters can be mounted on a support lock which is inturn mounted on a shaft which engages the saddle which moves around onthe split yoke and is provided with the feed mechanism to feed thecutters inwards as a cut is made as the saddle moves around on the splityoke.

A cutter 25 which acts to provide a chamfer is mounted on the supportblock 17 in a position substantially axial in relation to the shaft andthis cutter is arranged so that it can move from a cutting position to aposition where it is out of action (shown by dotted line), which canconveniently be achieved by mounting the cutter on a holder which ismounted on a pivot 27 on the support block so that it can besubstantially co-extensive with the shaft but can be folded down to beout of the cutting position, a spring blade 26 normally holding thecutter in either its cutting or its folded location. The cutter 25 has acutting edge shaped to produce the chamfer by having its cutting edge atthe required angle relative to the axis of the pipe to be cut.

The actual shape of the cutters can be considerably varied and, forinstance, in the case of the parting tool type or the type which forms agroove which is later cut by a second cutter, the tool can have asymmetrical point on it which cuts the groove, that is the point isarranged symmetrically about a central axis of the cutter and this caneither be of a gradual taper or of a steep taper according to what isrequired. Instead of having a symmetrical cutter, the cutter could forinstance have a first section which is shaped as a parting tool whichwill sever the pipe but biased in one direction and extending upon thefirst section on the other side can be a second portion which makes ashaping cut such as a bevel on the cut end at the outer part of the cut.

Thus the tool can have an axial face joining a sloping face on one sideof the centre line of the tube and a sloping face of a different shapeon the other side of the centre line but commencing at the point wherethe first surface ends.

By mounting the cutters on a support block on a shaft which can beprovided with the feed mechanism to feed the cutters into actuation asthe saddle moves around on the split yoke, a simple and effectivearrangement is achieved which can have either a single or plurality ofcutters and which can allow some lateral movement of the cutter wherethis is required but it will be realized that different methods ofsupport of the cutters are possible and the invention is not to belimited to the form just described. For instance the saddle could haveon it a first cutter which is fixed to form a groove initially to guidethe main cutter or this can be movable so that it can have upwarddisplacement against a loading force if that is required to counter thedistortion which occurs in a pipe as it is being cut as previouslydescribed, and a final cutter can be used on the saddle somewhat remotefrom the first bevelling or shaping cutter which again can be providedwith lateral movement against an urging force tending to hold it in apreselected position.

The cutters can be lubricated by a wick or other device, and the cutterscan have a sharpener arranged to allow ready sharpening in the case ofwheel cutters to maintain the required edge as the cutters rotate.

It will be realized from the foregoing that a simple and effectivedevice results from this invention which can be simply attached to apipe at an area where a cut is to be made and by driving the saddlearound on the split yoke, a cutting and/or shaping tool carried by thesaddle will channel or groove the pipe to cut the pipe by making one ormore passes of the saddle around on the split yoke while feeding in thecutting tool to make the required depth of cut.

The claims defining the invention are as follows:
 1. A pipe cutter forcutting pipes of plastics material, said cutter comprising: a split yokeconfigured to clamp on a pipe to be cut, a saddle guided against one endface of the yoke and movable on the yoke to rotate around the axis ofthe yoke, and a cutter disposed on a cutter holder mounted on the faceof the saddle remote from the said yoke and operable to engage and cutthe pipe in the region outside of the said split yoke and the saidsaddle as the saddle moves around the yoke, said yoke comprising twosemicircular parts pivoted to each other at one of their ends, and aclamp to clamp the other ends together whereby a pipe may be insertedinto the cutter when the yoke is in the opened position, and said saddlebeing circular and also formed of two portions, the said saddle havingan in-turned flange engageable with an internal circumferential slot inthe yoke, said two portions at one of their respective adjacent endsbeing joined by a connecting link, said link being pivoted to saidadjacent ends, said other ends of said portions being engageable by aprotuberance on one end engaging in a socket in said other end, wherebywhen the hinged portions of the yoke and saddle are aligned, said yokeand saddle can be opened and closed simultaneously, and means forrotating the said saddle on the said yoke when the said yoke is in theclosed position.
 2. A pipe cutter as defined in claim 1; wherein saidcutter holder is adjustable radially of the pipe by a handle and guideslidably engaging a support on said yoke, said handle having a screwthread engaging a springloaded ratchet whereby the ratchet allows rapidinward movement and rotation of the handle about its longitudinal axisto provide fine depth adjustment, said ratchet being manually releasedto allow rapid withdrawal of the cutter.
 3. A pipe cutter as defined inclaim 1; wherein the cutter is a rotary blade cutter mounted on a shaftparallel to the axis of the pipe, said rotary blade cutter being biasedby a spring against a stop in a direction to move said cutter towardsthe yoke, whereby in operation said cutter can move axially of the pipedue to the deflection of the pipe during cutting.
 4. A pipe cutter asdefined in claim 1; wherein said cutter holder carries a chamfer cuttercomprising a blade pivoted to the holder to be swung into a cuttingposition from a retracted position, said chamfer cutter comprising anangled blade having its cutting edge at an angle to the axis of the pipeso as to produce a chamfer on the cut end of the pipe.
 5. A pipe cutteras defined in any one of claims 1, 2, 3 or 4 characterised in that theyoke has a handle, the handle being positioned to be parallel to thehandle on the saddle in a position to open the yoke, said handle on theyoke being a sleeve over a leg, whereby the sleeve can be removed andpositioned in a socket angularly offset from the leg to provide a standfor the pipe cutter, said handle on the saddle being of lesser length toallow it to move the saddle around the yoke.